Automatic electrical air cleaner



Aug. 21, 1945. v DAHLMAN 7 2,383,112

AUTOMATIC ELECTRICAL AIR CLEANER Filed June 5, 1943 4 Sheets-Sheet 1 5Vim 2 BAHAMA/V INVENTO/Z 5 5;; m

A TTUk/YE Y 1945- v. DAHLMAN I AUTOMATIC ELECTRICAL AIR CLEANER 4Sheets-Sheet 2 Filed June 5, 1943 Aug. 21, 1945. v. DAHLMAN 2,333,112

AUTOMATIC ELECTRICAL AIR CLEANER Filed June 5, 1943 4 Sheets-Sheet 3llv'vslvrolz ATTOZ/VEY Aug. 21, 1945.

V. DAHLMAN AUTOMATIC'ELECTRICAL AIR CLEANER Filed June 5, 1945 4Sheets-Sheet 4 IN VENTOZ Patented Aug. 21, 1945- Verner Dahlman,Louisville,

American Air Filter Company, Ky., a corporation of Delaware Ky.,asslgnor to Inc., Louisville,

Application June 5, 1943, Serial No. 489,849

17 Claims.

This invention relates to automatic electrical air cleaners of theelectrostatic precipitating type disclosed in my copending application,Serial Number 479,665, filed March 18, 1943, wherein:

.a series of spaced movable precipitating plates are mounted formovement along a path having gas-cleaning and filter-cleaning areaswhile another series of spaced stationary precipitating plates arestationarily mountedin the gas-cleanlng area to interleavethe movableplates as they pass through such area, the interleaved platescooperating to form gas passages therebetween in which an electrostaticprecipitating field is established. hi this type of cleaner, some of thedust is deposited on the stationary plates where it slowly collects butmost of the dust is deposited upon the moving plates and carried to thefiltercleaning or clipping area where it is dipped in, and therebysubjected to the washing action of, an oil bath. The precipitated dustclings tenaciously to the plates with the result that dipping them inthe oil bath is not effective to prevent a gradual accumulation of dustthereon. The present in vention relates to means for preventing theaccumulation of dust on either or both sets of plates.

The principal object of the invention is to provide a simple form ofmeans by which either or both sets of plates may automatically beintermittently cleaned to remove any accumulated dust.

Another object is to provide means by which both sets of plates may beautomatically wiped at least once during each revolution of the movableplates. v

An air cleaner embodyingthis invention is illustrated in theaccompanying drawings wherein:

Figure 1 is vertical central section through the cleaner, the sprocketchains being omitted together with some of the movable plate cells for Ithe sake of clearness; l

Figure 2 is a schematic view of the casing as it appears in Fig. 1 buton-a smaller scale with elements 8 relatively enlarged for sake of clearness.

Figure 3 is a. section along line 3-3 of Fig. 2; Figures 4 and 5 are topplan and side elevational views of corresponding link portions of theconveyor chain; I

Figure 6 is a section along line 6--6 of Fig. 5; Figure 7 is ahorizontal sectional view corresponding to one taken on an enlargedscale along line 1-7 of Fig.1 but showing the movable plates in planinstead of in section for the sake of clearness;

Figure 8 is a side elevational view of the stationary wiping assemblyfor the movable plates;

Figure 9 is a partly broken top plan view of the stationary wipingassembly shown in Fig. 8, this view,- being shown in relation to a pairof approaching movable plates;

Figure 10 is a plan view of the m vable wipinc assembly for thestationary plates, this yiew corresponding to one taken along lineIll-l0 of Fig. 1 except for the omission of the stationary plates, andbeing shown in relation to the sprocket chains;

Figure 11 is a side elevation of the movable wiping assembly for thestationary plates;

Figure 12 is an end elevation of the movable wiping assembly for thestationary plates and correspond to the right end of the assembly shownin Fig. 10, except that it omits the sprocket chains shown in Fig. 10;

Fig. 13 is a perspective of the housing which carries and partiallyencloses the insulators of the movable wiping assembly; and

Figure 14 shows, on an enlarged scale, the manner in which the wiperassembly for the stationary plates pushes back the wiper assembly forthe movable plates as it passes the latter.

As illustrated in Figures 1-7, th cleaner conventionally includes: ahousing, an upright conveyor; an ionizer; and a plate-type electrical orelectrostatic precipitator.

The housing I conventionally includes: a bottom filter-cleaning or platedipping area in the form of an oil bath 2; an air or gas passagewayextending horizontally through the casing above the bath from anupstream or front gas inlet 3 successively through a front gas-cleaningarea 4, a central conveyor area 5,.and a rear gascleaning area 6 to adownstream or rear gas outlet I. The front and rear limits of theconveyor area are defined by front and rear conveyor guides 8 mounted oneach vertical side wall of the casing I.

The conveyor conventionally includes: upper and lower shafts 9; a pairof laterally spaced sprocket Ill on each shaft; a pair of laterallyspaced sprocket chains ll, one encircling each upper and lower sprocketwith front and rear flights lying within the channels of the adjacentfront and rear conveyor guide 8, each chain be ing composed of alternateand intermediate links, the altemate links being formed by straps I2,one of which has a lug Rd and the intermediate links being formed bystraps l3; and a bent rigid handle-like strap [4 secured to each lug lZaand cooperating therewith to form eye IS.

The ionizer I6 is conventionally mounted on the outside of the housing Iover the gas inlet opening 3. It conventionally includes: a groundedassembly of electrodes I1, and an insulated assembly of fine wireelectrodes I8.

The dust collecting portion of the precipitator conventionally includestwo series or set of cells, one set being movable and preferablygrounded and the other set being stationary, preferably insulated fromthe frame, and maintained at a relatively high electrical potential.Each cell, both movable and stationary, consists of a, numher ofpreferably plane, spaced parallel plates fixed to a crossbar. Eachmovable cell. is secured to the conveyor and held in a position suchthat the spaced plates thereof bodily move, in vertical planespreferably parallel to their major surfaces, along endless paths whichextend through each gas cleaning area and the bottom plate dipping area.Each stationary cell is fixedly secured to the frame, adjacent one gascleaning area or the other, in a manner such that the spaced platesthereof extend vertically within the adjacent gas cleaning area andcentrally between the fixed paths of the spaced movable plates so as tointerleave said paths and thus interleave the movable plates as theypass through such ga cleaning areas, the interleaved plates cooperatingto form gas passages therebetween.

Each movable cell comprises: an assembly of precipitating plates lQapresenting opposite side edges and opposite gas-flow edges respectively,the opposite side edges forming opposite side faces and the oppositegas-flow edges forming opposite gas-flow: faces; and a framework securedto one of the gas-flow faces so as to leave the other gasflow face andboth side faces of the assembly open suiflciently 'to permit its beinginterleaved with and, moved sidewise relatively to, another similarlyopen assembly. The framework is composed of upper and lower horizontalcross bars 22 and vertical end plates 24a, plates l9a being secured tothe framework through fingers 23' projecting from cross bars 22 and thecells as a whole being mounted on the conveyor chains by means of pins25 projecting outwardly from end plates 24a into the eyes E of theconveyor chain. The space between each conveyor guide 8 and the adjacentmovable cells is sealed by a stationary guide 26 adjustably secured tothe guide 8 and frictionally engagi the cells.

The stationary cells similarly include: an interleavable assembly ofplates IBD; and a. framework composed of cross bars 22, fingers 23, andend plates 24b. These cells are. stationarily mounted on, but insulatedfrom, the housing I by bolting the end plates 24b to vertical bars 21,the upper and lower ends of which are secured to insulators 28 carriedby the housing.

In operation: 11,000 to 13,000 volts are impressed across the ionizer;5,000 to 7,000 volts are impressed across the precipitating plates; airor gas is drawn or forced through the gas passageway; and the conveyoris moved in the direction indicated, by a suitably controlled drivemechanism (not shown) in accordance with the usual practice of about /4"every twelve minutes. As the movable plates pass upwardly out of the oilbath, they interleave the stationary plates in the front gas-cleaningarea and as they pass downwardly on the other side of the cleaner towardthe oil bath, they interleave the stationary plates in the reargas-cleaning area. During the interleaving intenval, dust iselectrically precipitated on both sets of plates but principally p n themovable plates. Heretofore dust has accumulated on the movaible platesbecause the action of the oil bath during the dipping interval wasinsufllcient to effect a thorough cleaning of the movable plates.

In accordance with my invention, means are positioned relatively to oneset of plates and arranged to present laterally-spaced,vertically-arranged, interleava'ble wipers which interleave such platesupon relative sidewise motion therebetween and which during such motionwipe the precipitating face of the interleaved Plates so as to removethe precipitated dust therefrom. Relative sidewise motion, between thewipers and the on the movable plate conveyor and arranging them tointerleave the stationary plates as they pass through the gas-cleaningarea occupied by such plates. With this arrangement means are alsoprovided to move the stationary wipers aside as the movable wipers passthrough the wiping area normally occupied by the stationary wipers.

The stationary wiping means for the movable plates may be mounted on thehousing at any point along the path of the movable plates but preferablyit is mounted in the oil bath 2 so that the wiping elements will besubjected to the washing action of the oil. This means comprises: aframework; and interleavable wipers carried by and projecting from theframework. The framework includes: a. pair of vertically-arranged,laterally-spaced arms 30 and a. cross bar 3! extending horizontally fromthe mid-section of one arm 30 to the mid-section of the other andrigidly secured to both. This framework is pivotally mounted on thehousing, for movement from the operative position shown in Figure l tothe inoperative position shown in Fig. 14, by rotationally securing thearms 30, adjacent their lower ends, to pins 32. The framework isresiliently urged toward and held in its operative position by suitablesprings 33 extending between the housing and the lower ends of the armsand secured to both.

A series of laterally-spaced and vertically-arranged wipers, one foreach end face of the movable cells and one for each space between theadjacent precipitating faces of adjacent plates in the cell, is mountedon the cross bar 3|. Each wiper includes: a wiping element 36 composedof a sheet of any suitable material such as felt, leather, etc., andfolded along a vertical axis to form a V in horizontal outline. Thematerial should be sumciently stiff and resilient that it tends toresume its original fiat shape. The fold line of each wiping element 34is nested in a U- shaped metal channel member 3'5, the lower end ofwhich is secured to the cross bar 3| by horizontal side flanges 36 and avertical back flange 31, all of which 'are welded or otherwise rigidlyattached to bar 3|. Each wiping element 34 is held within channel member35 by a V-shaped spreader 38 which is nested within the element 34 toclamp it against channel member 35. The outer ends of the spreader 38diverge in order to spread the outer ends of the wiping element 34apart. The outer ends of adjacent elements 34 preferably engage eachother so that when a. movable plate I9a. passes between adjacentelements, opposite faces of the plate will be firmly engaged and wipedby such elements.

The movable wipers for the stationary plates are positioned between twoadjacent alternate cells on the conveyor and secured directly to, butpreferably insulated from, th conveyor chains I I. It likewisecomprises: a framework; and interleavable wipers carried by andprojecting from the framework. The framework includes a base member orinsulator housing in the form of a flared tray 39, the end marginaledges of which are provided with securing flanges 40. As indicated inFig. 10, the flanges 40 may be secured cell is mounted on cross bar 43.Since the movable wipers for the stationary plates are constructed in amanner substantially identical to the stationary Wipers for the movableplates, it

should suilice to note that they include: a wiping element 44; a channelmember 45 having side flanges 46 and a back flange 41; and a spacer 48.The wiping elements 44 at each end of theseries are in the form of halfloops while the intermediate elements in the series are in the form ofcomplete loops. The elements 44 are wipers pass through the gas-cleaningareas ooparallel plate elements: a wiper assembly composed of a similarseries of spaced parallel platewiping elements; means mounting one ofsaid assemblies on the frame with. its elements extending into said pathat the plate-wiping area; means movably mounting the other assembly uponthe frame for movement along said path with its elements. extending intosaid path; the elements of both assemblies being so arranged in saidpath that the wiping elements interleave, and Wipe the precipitatingfaces of, the plate elements during movement of the movable assemblythrough the plate-wiping area; and means for so moving the movableassembly. I

2. In the cleaner of claim 1 wherein: the plate assembly is mounted inthe wiping area; and the wiping assembly is mounted for movement alongcupied by the stationary plates, they will interleave and wipe thestationary plates in such areas. In this manner both sets of plates willbe cleaned once during each revolution of the conveyor and therebyprevented from accumulating an unchecked deposit of dust.

However, when the movable wipers pass the area normally occupied by thestationary wipers, it is necessary to move the stationary wipers aside.To this end. the securing flanges 40 of the movable wipers carry endplates 49, the outer ends of which are provided with cams 50. The cams50 of the movable wipers are positioned to engage the arms 30 of thestationary wipers when the movable wipers closely approach thestationary wipers. As the movable wipers continue their movement towardand through the area of the stationary wipers, the cams 50, throughtheir engagement with the arms 30, swing the stationary wipers to theirinoperative position and hold them therein. When the movable wipers passbeyond the stationary wiping area, the'cams 50 release the arms 30permitting the springs 33 to return the stationary wiper assembly to itsoperative position. i

As indicated previously, the cells have side faces and gas-flow faceswith a framework securing one gas-flow face only so as to leave theother gasflow face and both side faces opensufliciently to permit itsbeing interleaved with, and moved sidewise relatively to, a similarlyopen oppositely disposed assembly. Both wiper assemblies are similar tothe cells, in this respect, in that they have corresponding side facesand end faces (corresponding to the gas-flow faces of the cells) with aframework secured to one end face only so as to leave the other end faceand both side faces open sufficiently to permit its being interleavedwith, and moved sidewise relative to, a similarly open oppositelydisposed assembly.

Having described my invention, I claim:

1. In an electrical gas cleaner having aframe said path and through saidarea.

3. In the cleaner of claim 1 wherein: the wiping assembly is mounted inthe wiping area; and the plate assembly is mounted for movement alongsaid path and through said area. I

4. In an electrical gas cleaner having a frame and means on the frameprescribing a path of movement extending through a plate-wiping area: aplate'assembly composed of a framework and a series of spaced parallelplate elements secured to and projecting from the framework; a wiperassembly composed of a framework and a series of spaced parallel platewiping elements secured to and projecting from the framework; meansmounting the framework of one assembly on the frame at one side of saidpath with its elements extending into said path at the plate-wipingarea;

means movably mounting the framework of the other assembly upon theframe for movement along the opposite side of said path with itselements extending into said path; the elements 0| both assemblies beingso arranged in said path that the wiping elements interleave, and wipe te precipitating faces of, the plate elements during movement of themovable assembly through the plate-wiping area; and means for so movingthe movable assembly.

5. In the cleaner of claim 4 wherein: the plate assembly is mounted inthe wiping area; and the wiping assembly is mounted for movement alongsaid path and through said area.

6. In the cleaner of claim 4 wherein: the wiping assembly is mounted inthe wiping area; and the plate assembly is mounted for movement alongsaid path and through said area. 7

'7. An electrical gas cleaner comprising: a mov able assembly of spacedparallel plates of one electrical sign mounted for movement through apath having a gas cleaning area and aplate-wiping area; a stationaryassembly of spaced parallel plates of the opposite electrical signstationarily mounted in the gas cleaning area and so arranged therein astointerleave, and form gas passages with, the movable plates passingthrough the gas cleaning area: a relatively stationary assembly ofspaced parallel plate-wiping elements mounted in the plate-wiping areaand so arranged therein as to interleave, and wipe the precipitatingfaces of, the movable plates passing through the wiping area; and meansfor moving the movable plate assembly through said areas.

8. An electrical gas cleaner comprising: a mov able assembly of spacedparallel plates of one electrical sign mounted for movement through apath having a gas cleaning area; a stationary assembly of spacedparallel plates of theo-pposite electrical sign stationarily mounted inthe gas cleaning area and so arranged therein .as to interleave, andform gas passages with, the movable plates passing through the gascleaning area; a movable assembly of spaced parallel plate-wipingelements mounted for movement through said path and 50 arranged thereinas to interleave, and wipe the precipitating faces of, the stationaryplates in the gas cleaning area as the movable wiping elements passthrough said area; and means fOr moving the movable plate and wipingassemblies serially through said area.

9. An electrical gas cleaner comprising: a movable assembl of spacedparallel plates of one electrical sign mounted for movement through apath having a gas cleaning area and plate-wiping area; a stationaryassembly of spaced parallel plates of the opposite electrical signstationarily mounted in the gas cleaning area and so arranged therein asto interleave, and form gas passages with, the movable plates passingthrough the gas cleaning area; a movable assembly of spaced parallelplate-wiping elements mounted for movement through said path and soarranged therein as to interleave, and Wipe the precipitating faces of,the stationary plates in the gas cleaning area as the movable wipingelements pass through said area; a relatively stationary assembly ofspaced parallel plate-wiping elements mounted in the plate-wiping areaand so arranged therein as to interleave, and wipe the precipitatingfaces of, the movable plates passing through the wiping area; and meansfor moving the movable plate and wiping assemblies serially through saidareas.

10. The gas cleaner of claim 9 wherein: means are provided to move therelatively stationary wiping assembly out of the wiping area during themovement of the movable, wiping assembly through said area.

11. The gas cleaner of claim 9 wherein: the relatively stationary wipingassembly is arranged for movement into and out of said wiping area;means are provided normally urging said assembly into said area; andmeans, associated with the movable wiping assembly, for moving thestationary wiping'assembly out of said area during the travel of themovable wiping assembly through said area.

12. An electrical gas cleaner comprising: a series of movable cells,each composed of an assembly of spaced parallel plate elements of oneelectrical sign, mounted for serial movement along a path having a gascleaning area with their plate elements extending into said path; atleast one stationary cell, composed of spaced parallel plate elements ofthe opposite electrical sign, stationarily mounted with its platesextending into the gas cleaning area and so arranged therein as tointerleave and form gas passages with the plate elements of the movablecells passing through the gas cleaning area; a movable wiping unit,composed of spaced parallel plate-wiping elements, interposed in theseries of cells and mounted for movement therewith along said path withits plate-wiping elements extending into said path movable cellsserially through said area.

13. An electrical gas cleaner comprising: a series of movable cells,each composed of an assembly of spaced parallel plate elements of oneelectrical sign, mounted for serial movement along a path having a gascleaning area and an oil bath area with their plate elements extendinginto said path; at least one stationary cell, composed of spacedparallel plate elements of the opposite electrical sign, stationarilymounted with its plate extending into the gas cleaning area and soarranged therein as to interleave and form gas passages with the plateelements of the movable cells passing through the gas cleaning area; arelatively stationary wiping unit, composed of spaced parallelplate-wiping elements, mounted with its elements extending in the oilbath area and so arranged therein as to interleave, and wipe theprecipitating faces of, the movable plates passing through the oil batharea; and means for moving the movabl cells serially through said areas.

14. An electrical gas cleaner comprising: a series of movable cells,each composed of an assembly of spaced parallel plate elements of oneelectrical sign, mounted for serial movement along a path having a gascleaning area and an oil bath area with their plate elements extendingintosaid path; at least one stationary cell, composed of spaced parallelplate elements of the opposite electrical sign, stationarily mountedwith its plates extending into the gas cleaning area and so arrangedtherein as to interleave and form gas passages with the plate elementsof the movable cells passing through the gas cleaning area; a movablewiping unit, composed of spaced parallel plate-wiping elements,interposed in the series of cells and mounted for movement therewithalong said path with its plate-wiping elements extending into said pathand so arranged therein as to interleave, and wipe the precipitatingfaces of, the stationary plates in the gas cleaning area as the movablewiping elements pass through said area; a relatively stationary wipingunit, composed of spaced parallel platewiping elements, mounted with itselements extending in the oil bath area and so arranged therein as tointerleave, and wipe theprecipitatlng faces of, the movable platespassing through the oil bath area; means for moving the movabl wipingunit and movable cells serially through said areas; and means for movingthe wiping elements of the relatively stationary wiping unit out of theoil bath area of said path during the movement, of 'the movable wipingunits through such area.

15. The cleaner of claim 14 wherein: each cell and wiping unit includesa framework to which its spaced parallel elements are secured and fromwhich they project; each framework of a stationary cell and unit ismounted on one side of the path; and each framework of a movable celland unit is mounted on the opposite side of the path 16. A plate wipingunit of the class described comprising: a framework; a row-like seriesof plate wipers secured to said framework and projecting outwardlytherefrom in parallel relationship to provide a series of spacedparallel passageways between wipers through which a series of spacedparallel precipitating plates may pass, said wipers being arranged towipe the faces of the plates passing between them.

17. The unit of claim 16 wherein at least one wiper includes: a stiffspine secured at one end to the framework and projecting outwardlytherefrom; and a wiping element secured to the spine along its lengthand arranged to present side faces which divergingly extend laterallyfrom the spine.

VERNER DAHLMAN.

